This invention relates to dental syringe tip assemblies, and more particularly to dental syringe tip assemblies having a disposable tip, an innovative adaptor and a captivated thumb nut.
For the past twenty-five years, dentists have been using a three-way syringe. An air tube and a water tube join together at the handpiece. Two operating buttons are provided on the handpiece body to allow activation by the dentist of the air or water. By depressing the air button, air flows out of the tip into the appropriate area of the patient's mouth to dry the field of operation. By depressing the water button, a passive flow of water is emitted to clean and float away debris and congestion from the field of operation. By depressing both buttons simultaneously, a spray of air and water is emitted which flushes away debris which can then be vacuumed from the oral cavity. Typical of a three-way syringe assembly is that shown in U.S. Pat. No. 3,874,083 to Buckley.
During these twenty-five years, there has only been one significant improvement made to this essential piece of dental equipment. In approximately 1979, the tip of the syringe was made removable to allow for sterilization. Before 1979, tips were disinfected and cleaned by simply wiping them with alcohol. With the development of the removable tip, sterilization of each tip could be accomplished through the use of steam or chemical heat procedures. However, if done with the appropriate frequency, the tip becomes clogged and unusable in several months. This is due to minerals and other impurities in the steam used in an autoclave which causes alkaline and calcium deposits to build up in the orifices of the tip which interrupt the flow of air and water from the tip. The air and water orifices in the tip are quite small, so that any irregularities occurring during fabrication will also decrease the life expectancy of the tip. Any plugging of the tip orifices results in both a loss of spray pressure as well as a loss of spray accuracy. Tips are conventionally made cut of metal and it would be cost prohibitive to discard a metal tip after only a single use.
With the rising incidence of communicable diseases such as hepatitis and acquired immune deficiency syndrome, extreme care must be taken to prevent the transmission of germs (viral or bacteria) from one patient to the next. With the conventional metal tips, it is necessary to sterilize the tip after each patient use. This is due to a condition that occurs in the end of the tip during use known as water retraction (also called suck-back or draw-back), which is a negative pressure applied to the water line. In a syringe, water retraction is used to prevent siphoning or dripping from the water line. When water retraction occurs, water, saliva and blood from the patient's mouth can be drawn back into the end of the tip and then passed on to the next patient. This provides the opportunity for the transfer of infection from one patient to the next. Also, latent bacterial growth can be promoted in both the tip and the entire water system lines because of the existence of this potentially contaminating material. Both the Center for Disease Control and the American Dental Association recommend that water lines be non-retracting. To further mitigate this possibility of cross-contamination from one patient to the next, the routine sterilization of handpieces as well as air/water syringes is desirable. In the case of handpieces and air/water syringes that cannot be sterilized, it is recommended that other complete cleaning and disinfection procedures be followed.
A disposable syringe tip is disclosed in U.S. Pat. No. 4,026,025 to Roderick S. Hunt. The plastic tip is disclosed as flexible and can be easily bent by hand without any special tools or heating. Such a flexible tip would suffer from the limitation that it would not function as a retractor. It is necessary when applying air, water or a spray to the patient's mouth to be able to use the syringe tip as a retractor to move the patient's tongue, cheeks or lips. If the syringe tip were flexible, it would fail to perform this important retraction function.
The syringe tip and mounting collet disclosed in the Hunt patent also have further design limitations. The chamfered surface on the end of the syringe tip effectively directs the air away from the water thereby impeding the formation of the water spray which is so important in a three-way syringe. The small circular air passages further limit the amount of air exiting the end of the tip and these air passages would be subject to being crimped closed when the flexible tip is bent. The syringe tip is press fit on the end of a small nipple on the collet in such a manner that the air and water pressure leaving the handpiece body and entering the syringe tip would lead to a loosening of the press fit thereby causing the syringe tip to dislodge from the nipple. This design is also not adaptable to most three-way piece syringe assemblies on the market.
It is an object of the present invention to alleviate the transmission of germs (viral or bacteria) which cause infection or disease, from one patient to the next, and to eliminate the need to resterilize a syringe tip after each use.
It is a feature of the present invention to provide a clear, plastic disposable rigid syringe tip that is discarded after its use on a single patient, as well as to provide a novel adaptor to connect the disposable syringe tip to the handpiece body.
It is an advantage of the present invention that a more sterile dental environment will be created as well as the flow of air, water or spray from the syringe to the oral cavity will be improved.
It is a further object of the present invention to provide novel adaptors for connecting syringe tips to the handpiece body and improving the flow and distribution of air and water into the patient's mouth.
It is a further feature of the present invention to provide adaptors being specially designed to receive various sealing rings and also adaptors provided with improved passageway configurations.
It is a further advantage of the present invention that the particular adaptors utilized prevent water and air leakage as well as improving the flow of water and air from the handpiece body through the adaptor and the syringe tip and into the patient's mouth.
It is a further object of the present invention to provide for an easy and simple connection and disconnection of the syringe tip from the adaptor while at the same time minimizing the possibility that the locking thumb nut securing the syringe tip to the adapter will become lost or misplaced. It is a further feature of the present invention to provide a captivated locking thumb nut assembly that prevents the locking thumb nut from becoming disengaged from the adaptor unless the locking thumb nut is oriented into a position in which disengagement is possible.
It is a further advantage of the present invention that a used syringe tip can be removed and replaced with a new syringe tip by merely loosening the captivated locking thumb nut and thus the locking thumb nut cannot become accidently separated from the adaptor, thus minimizing the loss or misplacement of the captivated locking thumb nut.
Other objects, features and advantages will become apparent when the detailed description and drawings of the present invention are considered.